1 /*
2 * CAIF Framing Layer.
3 *
4 * Copyright (C) ST-Ericsson AB 2010
5 * Author: Sjur Brendeland/sjur.brandeland@stericsson.com
6 * License terms: GNU General Public License (GPL) version 2
7 */
8
9 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
10
11 #include <linux/stddef.h>
12 #include <linux/spinlock.h>
13 #include <linux/slab.h>
14 #include <linux/crc-ccitt.h>
15 #include <net/caif/caif_layer.h>
16 #include <net/caif/cfpkt.h>
17 #include <net/caif/cffrml.h>
18
19 #define container_obj(layr) container_of(layr, struct cffrml, layer)
20
21 struct cffrml {
22 struct cflayer layer;
23 bool dofcs; /* !< FCS active */
24 };
25
26 static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt);
27 static int cffrml_transmit(struct cflayer *layr, struct cfpkt *pkt);
28 static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
29 int phyid);
30
31 static u32 cffrml_rcv_error;
32 static u32 cffrml_rcv_checsum_error;
cffrml_create(u16 phyid,bool use_fcs)33 struct cflayer *cffrml_create(u16 phyid, bool use_fcs)
34 {
35 struct cffrml *this = kmalloc(sizeof(struct cffrml), GFP_ATOMIC);
36 if (!this) {
37 pr_warn("Out of memory\n");
38 return NULL;
39 }
40 caif_assert(offsetof(struct cffrml, layer) == 0);
41
42 memset(this, 0, sizeof(struct cflayer));
43 this->layer.receive = cffrml_receive;
44 this->layer.transmit = cffrml_transmit;
45 this->layer.ctrlcmd = cffrml_ctrlcmd;
46 snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "frm%d", phyid);
47 this->dofcs = use_fcs;
48 this->layer.id = phyid;
49 return (struct cflayer *) this;
50 }
51
cffrml_set_uplayer(struct cflayer * this,struct cflayer * up)52 void cffrml_set_uplayer(struct cflayer *this, struct cflayer *up)
53 {
54 this->up = up;
55 }
56
cffrml_set_dnlayer(struct cflayer * this,struct cflayer * dn)57 void cffrml_set_dnlayer(struct cflayer *this, struct cflayer *dn)
58 {
59 this->dn = dn;
60 }
61
cffrml_checksum(u16 chks,void * buf,u16 len)62 static u16 cffrml_checksum(u16 chks, void *buf, u16 len)
63 {
64 /* FIXME: FCS should be moved to glue in order to use OS-Specific
65 * solutions
66 */
67 return crc_ccitt(chks, buf, len);
68 }
69
cffrml_receive(struct cflayer * layr,struct cfpkt * pkt)70 static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt)
71 {
72 u16 tmp;
73 u16 len;
74 u16 hdrchks;
75 u16 pktchks;
76 struct cffrml *this;
77 this = container_obj(layr);
78
79 cfpkt_extr_head(pkt, &tmp, 2);
80 len = le16_to_cpu(tmp);
81
82 /* Subtract for FCS on length if FCS is not used. */
83 if (!this->dofcs)
84 len -= 2;
85
86 if (cfpkt_setlen(pkt, len) < 0) {
87 ++cffrml_rcv_error;
88 pr_err("Framing length error (%d)\n", len);
89 cfpkt_destroy(pkt);
90 return -EPROTO;
91 }
92 /*
93 * Don't do extract if FCS is false, rather do setlen - then we don't
94 * get a cache-miss.
95 */
96 if (this->dofcs) {
97 cfpkt_extr_trail(pkt, &tmp, 2);
98 hdrchks = le16_to_cpu(tmp);
99 pktchks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
100 if (pktchks != hdrchks) {
101 cfpkt_add_trail(pkt, &tmp, 2);
102 ++cffrml_rcv_error;
103 ++cffrml_rcv_checsum_error;
104 pr_info("Frame checksum error (0x%x != 0x%x)\n",
105 hdrchks, pktchks);
106 return -EILSEQ;
107 }
108 }
109 if (cfpkt_erroneous(pkt)) {
110 ++cffrml_rcv_error;
111 pr_err("Packet is erroneous!\n");
112 cfpkt_destroy(pkt);
113 return -EPROTO;
114 }
115 return layr->up->receive(layr->up, pkt);
116 }
117
cffrml_transmit(struct cflayer * layr,struct cfpkt * pkt)118 static int cffrml_transmit(struct cflayer *layr, struct cfpkt *pkt)
119 {
120 int tmp;
121 u16 chks;
122 u16 len;
123 int ret;
124 struct cffrml *this = container_obj(layr);
125 if (this->dofcs) {
126 chks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
127 tmp = cpu_to_le16(chks);
128 cfpkt_add_trail(pkt, &tmp, 2);
129 } else {
130 cfpkt_pad_trail(pkt, 2);
131 }
132 len = cfpkt_getlen(pkt);
133 tmp = cpu_to_le16(len);
134 cfpkt_add_head(pkt, &tmp, 2);
135 cfpkt_info(pkt)->hdr_len += 2;
136 if (cfpkt_erroneous(pkt)) {
137 pr_err("Packet is erroneous!\n");
138 return -EPROTO;
139 }
140 ret = layr->dn->transmit(layr->dn, pkt);
141 if (ret < 0) {
142 /* Remove header on faulty packet. */
143 cfpkt_extr_head(pkt, &tmp, 2);
144 }
145 return ret;
146 }
147
cffrml_ctrlcmd(struct cflayer * layr,enum caif_ctrlcmd ctrl,int phyid)148 static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
149 int phyid)
150 {
151 if (layr->up->ctrlcmd)
152 layr->up->ctrlcmd(layr->up, ctrl, layr->id);
153 }
154